The subject of the present invention are compositions containing matrix polymer, graft polymer and special additive mixtures, their use for the production of moulded articles, as well as the moulded articles obtainable therefrom. The subject of the invention is also the additive combination.
ABS moulding compositions have already been used for many years in large quantities as thermoplastic resins for the production of all types of moulded parts. The property spectrum of these resins ranges from relatively brittle to extremely tough.
A special area of use of ABS moulding compositions is the production of moulded parts by injection moulding (e.g. housings, toys, vehicle parts), an important factor being in particular a very good flowability of the polymer material. Also, the moulded parts produced in this way must as a rule have a good notched-bar impact strength as well as a good resistance to thermal stresses.
The object therefore exists of achieving, for a given rubber content, a given rubber particle size and given matrix resin molecular weight, toughness values that are as high as possible while retaining the good thermoplastic flowability. In this connection the high toughness values should as far as possible be obtained independently of the type of matrix resin that is employed, and especially when using the styrene/acrylonitrile copolymers and xcex1-methylstyrene/acrylonitrile copolymers typical of ABS.
One possible way of improving the toughness of ABS polymers with a given rubber content, given rubber particle size and given matrix molecular weight is to add special silicone oil compounds (see EP-A 6521); however, disadvantages may arise such as poor paintability, unsatisfactory printability or impaired yield stress values (danger of stress whitening). The addition of minor amounts of EPDM rubber (see EP-A 412 370) or AES polymer (see EP-A 412 371) has also been described. Both methods require the use of considerable amounts of relatively expensive additive components however.
The use of large amounts of individual low molecular weight additive components may in special cases improve the processability, although this is normally offset by a negative effect on other properties such as for example toughness, modulus of elasticity and thermal stability.
It has now been found that by using special additive mixtures, ABS products can be obtained having a very good combination of notched-bar impact strength (at room temperature as well as at low temperatures) and excellent processability.
The invention provides thermoplastic moulding compounds or compositions containing
A) 5 to 95 wt. %, preferably 10 to 90 wt. % and particularly preferably 20 to 75 wt. % of one or more thermoplastic homopolymers, copolymers or terpolymers of styrene, xcex1-methylstyrene, nuclear-substituted styrene, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof,
B) 5 to 95 wt. %, preferably 10 to 90 wt. % and particularly preferably 25 to 80 wt. % of one or more graft polymers of
B.1) 5 to 90 parts by weight, preferably 20 to 80 parts by weight and particularly preferably 25 to 60 parts by weight of styrene, xcex1-methylstyrene, nuclear-substituted styrene, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof, on
B.2) 95 to 10 parts by weight, preferably 80 to 20 parts by weight and particularly preferably 75 to 40 parts by weight of at least one rubber having a glass transition temperature of xe2x89xa610xc2x0 C.
and
C) 0.05 to 10 parts by weight, preferably 0.1 to 8 parts by weight and particularly preferably 0.5 to 5 parts by weight, in each case per 100 parts by weight of A)+B), of a combination of at least 3 components selected from compounds I), II), III) and IV), wherein I) denotes a compound with at least one structural unit 
xe2x80x83where
M=metal, preferably Mg, Ca, Zn
n=valency of the metal M, preferably 1 or 2
II) denotes a compound with at least one structural unit 
xe2x80x83and at least one structural unit 
wherein R1 and R2 are, independently of one another, H or C1-C20 hydrocarbon radicals,
III) denotes a compound with at least one structural unit 
xe2x80x83and
IV) denotes a compound with structural units that are different from the specified structural units or combination of structural units contained in the compounds (I) to (III), i.e. the compounds (IV) contain none of the structural units or combinations of structural units contained in the compounds (I) to (III).
Preferably each of the compounds I) to IV) contains at least one terminal aliphatic C6-C32 hydrocarbon radical.
According to the invention suitable thermoplastic polymers A) are those of styrene, xcex1-methylstyrene, p-methylstyrene, vinyltoluene, halogenated styrene, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof.
The polymers A) are resin-like, thermoplastic and rubber-free. Particularly preferred polymers A) are those of styrene, methyl methacrylate, styrene/acrylonitrile mixtures, styrene/acrylonitrile/methyl methacrylate mixtures, styrene/methyl methacrylate mixtures, acrylonitrile/methyl methacrylate mixtures, xcex1-methylstyrene/acrylonitrile mixtures, styrene/xcex1-methylstyrene/acrylonitrile mixtures, xcex1-methylstyrene/methyl methacrylate/acrylonitrile mixtures, styrene/xcex1-methylstyrene/methyl methacrylate mixtures, styrene/(xcex1-methylstyrene/methyl methacrylate/acrylonitrile mixtures, styrene/maleic anhydride mixtures, methyl methacrylate/maleic anhydride mixtures, styrene/methyl methacrylate/maleic anhydride mixtures and styrene/acrylonitrile/N-phenylmaleimide mixtures.
The polymers A) are known and can be produced by free-radical polymerisation, in particular by emulsion, suspension, solution or bulk polymerisation. The polymers preferably have molecular weights {overscore (M)}w of 20,000 to 200,000 and intrinsic viscosities [xcex7] of 20 to 110 ml/g (measured in dimethylformamide at 25xc2x0 C.).
Suitable rubbers for the production of the graft polymers B) are in particular polybutadiene, butadiene/styrene copolymers, butadiene/acrylonitrile copolymers, polyisoprene or alkyl acrylate rubbers based on C1-C8 alkyl acrylates, in particular ethyl acrylate, butyl acrylate and ethylhexyl acrylate.
The acrylate rubbers may optionally contain up to 30 wt. % (referred to the rubber weight) of monomers such as vinyl acetate, acrylonitrile, styrene, methyl methacrylate and/or vinyl ether incorporated by copolymerisation. The acrylate rubbers may also contain small amounts, preferably up to 5 wt. % (referred to the weight of rubber) of crosslinking, ethylenically unsaturated monomers incorporated by polymerisation. Crosslinking agents are for example alkylene diol diacrylates and methacrylates, polyester diacrylates and methacrylates, divinyl benzene, trivinyl benzene, triallyl cyanurate, allyl acrylate and methacrylate, butadiene and isoprene. Graft bases may also be acrylate rubbers with a core/shell structure, with a core of crosslinked diene rubber of one or more conjugated dienes such as polybutadiene, or a copolymer of a conjugated diene with an ethylenically unsaturated monomer such as styrene and/or acrylonitrile.
Further suitable rubbers are for example the so-called EPDM rubbers (polymers of ethylene, propylene and a non-conjugated diene such as for example dicyclopentadiene), EPM rubbers (ethylene/propylene rubbers) and silicone rubbers that may optionally have a core/shell structure.
Preferred rubbers for the production of the graft polymers B) are diene rubbers and alkyl acrylate rubbers as well as EPDM rubbers.
The rubbers in the graft polymer B) are present in the form of at least partially crosslinked particles having a mean particle diameter (d50) of 0.05 to 20 xcexcm, preferably 0.1 to 2 xcexcm and particularly preferably 0.1 to 0.8 xcexcm. The mean particle diameter d50 is determined by ultracentrifuge measurements according to W. Scholtan et al., Kolloid-Z. u.Z. Polymere 250 (1972), 782-796, or by evaluating electron microscope images.
The polymers B) may be produced by free-radical graft polymerisation of the monomers B.1) in the presence of the rubbers B.2) to be grafted on.
Preferred processes for producing the graft polymers B) are emulsion, solution, bulk or suspension polymerisation and combinations known per se of these processes. Particularly preferred graft polymers B) are ABS polymers.
Most particularly preferred polymers B) are products that have been obtained by free-radical polymerisation of mixtures of styrene and acrylonitrile, preferably in a weight ratio of 10:1 to 1:1, particularly preferably in a weight ratio of 5:1 to 2:1, in the presence of at least one rubber built up predominantly from diene monomers (preferably polybutadiene that may contain up to 30 wt. % of styrene and/or acrylonitrile incorporated as comonomers) and having a mean particle diameter (d50) of 100 to 450 nm, most particularly preferably in the presence of two rubbers built up predominantly from diene monomers (preferably polybutadiene that may contain up to 30 wt. % and/or acrylonitrile incorporated as comonomers) and having a) a mean particle diameter (d50) of 150 to 300 nm and b) a mean particle diameter (d50) of 350 to 450 nm, in a weight ratio (a):(b)=10:90 to 90:10, preferably 30:70 to 60:40.
The rubber content of the polymers B) is preferably 40 to 95 wt. %, particularly preferably 50 to 90 wt. % and most particularly preferably 55 to 85 wt. %.
As individual components of the additive mixture C) the following compounds are for example suitable and preferred:
As component I)
magnesium stearate, calcium stearate, zinc stearate, magnesium montanate, calcium montanate, zinc montanate, magnesium behenate, calcium behenate, zinc behenate, magnesium oleate, calcium oleate, zinc oleate; magnesium stearate and calcium stearate are preferred, magnesium stearate being particularly preferred.
As component II)
esters of 3,5-di-tert.-butyl-4-hydroxyphenylacetic acid with monohydric or polyhydric alcohols, such as for example and preferably decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, octadecanol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, ethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylol propane.
Esters of xcex2-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, such as for example and preferably decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, octadecanol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, ethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylol propane.
Esters of xcex2-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols, such as for example and preferably decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, octadecanol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, ethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylol propane.
Esters of xcex2-(3,5-dicyclohexyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, such as for example and preferably decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, octadecanol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, ethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, 3-thiaundecanol, 3-thiapentadecanol, trimethylol propane.
Preferred are esters of xcex2-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid and/or of xcex2-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acid, and particularly preferred are esters of xcex2-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid.
As component III)
ethylenediamine bisstearyl amide, erucic acid amide, oleic acid amide, stearic acid amide, behenic acid amide, montanic acid amide; ethylenediamine bisstearyl amide and/or erucic acid amide are preferred, ethylenediamine bisstearyl amide being particularly preferred.
As component IV)
paraffin oils, hydrocarbon waxes, low molecular weight polystyrene produced by using C8-C18 alkyl mercaptans as molecular weight regulators with mean molecular weights ({overscore (M)})w between 2,000 and 15,000, preferably between 2,500 and 12,000 and particularly preferably between 3,000 and 10,000, low molecular weight styrene/acrylonitrile copolymer produced by using C8-C18 alkyl mercaptans as molecular weight regulators with mean molecular weights ({overscore (M)})w between 2,000 and 15,000, preferably between 2,500 and 12,000 and particularly preferably between 3,000 and 10,000, low molecular weight xcex1-methylstyrene/acrylonitrile copolymer produced by using C8-C18 alkyl mercaptans as molecular weight regulators with mean molecular weights ({overscore (M)})w between 2,000 and 15,000, preferably between 2,500 and 12,000 and particularly preferably between 3,000 and 10,000, low molecular weight poly(methyl methacrylate) produced by using C8-C18 alkyl mercaptans as molecular weight regulators with mean molecular weights ({overscore (M)})w between 2,000 and 15,000, preferably between 2,500 and 12,000 and particularly preferably between 3,000 and 10,000, C6-C32 alkanols, for example and preferably stearyl alcohol, and C6-C32 alkenols, for example and preferably oleyl alcohol.
Preferred are paraffin oils, low molecular weight styrene/acrylonitrile copolymers or xcex1-methylstyrene/acrylonitrile copolymers, and particularly preferred are paraffin oils or low molecular weight styrene/acrylonitrile copolymers or, in each case, mixtures thereof.
Preferably all the components I), II), III), and IV) have a molecular weight above 300, preferably above 400 and particularly preferably above 500.
The quantitative ratios for the use according to the invention of at least three components selected from the components I), II), III), and IV) may be varied within wide ranges. The ratios are selected so that the following relationship is observed
Particularly preferred mixtures contain 15 to 65 wt. % of graft polymer of 25 to 60 parts by weight of styrene, xcex1-methylstyrene, acrylonitrile, N-phenylmaleimide or mixtures thereof on 75 to 40 parts by weight of polybutadiene,
85 to 35 wt. % of thermoplastic copolymer of 5 to 40 parts by weight of acrylonitrile and 95 to 60 parts by weight of styrene, xcex1-methylstyrene, N-phenylmaleimide or mixtures thereof, and
0.5 to 5 parts by weight per 100 parts by weight of A+B of a combination of at least 3 components selected from
I) magnesium stearate,
II) octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate or tetradecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate or dodecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate,
III) ethylenediamine bisstearyl amide
IV) paraffin oil or low molecular weight styrene/acrylonitrile copolymer.
The mixtures according to the invention containing A), B) and C) and optionally conventional additives such as processing aids, stabilisers, pigments, antistatics and fillers are prepared by mixing the respective constituents in a manner known per se simultaneously or successively at room temperature or at elevated temperature, following which the resultant mixtures are melt-compounded or melt-extruded at temperatures of 150xc2x0 C. to 300xc2x0 C. in conventional equipment such as internal mixers, extruders or double-shaft screw extruders.
The moulding compounds or compositions of the present invention may be used to produce moulded articles of all types, in which connection conventional production procedures may be employed, and in particular moulded articles may be produced by injection moulding.
A further type of processing of the moulding compositions according to the invention is the production of moulded articles by thermoforming from sheets or films previously fabricated by known methods.
The subject of the present invention is therefore furthermore the process for the production of the moulding compositions, their use for the production of moulded articles, as well as moulded articles obtainable therefrom. The subject of the present invention is moreover the additive combination according to component C.